List of Prior Art Literatures
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Venezuelan equine encephalitis virus (VEE), belonging to alphavirus genus of the family Togaviridae, is an important pathogen of epidemics in humans and of epizootics in some animals (Johnston et al., 1996). VEE causes a spectrum of human diseases ranging from inapparent infection to acute encephalitis (Franck et al; 1970; Johnson et al., 1968). Since the VEE genome is composed of positive sense RNA, its nucleic acid is infectious independent of the complete viral particle (Johnston et al., 1996). Furthermore, VEE is highly infectious by aerosol inhalation in humans (Johnston et al., 1996). Thus, VEE is a potential biological warfare and bioterrorist agent of concern. Therefore, simple, stable, and efficient immunoassays are required for rapid identification of VEE in environmental or clinical samples in order that immediate therapeutic and preventive counter measures can be taken to limit the epidemic spread of VEE infection.
The present inventors have previously cloned and characterized several single-chain variable fragment antibodies (scFv Abs) against VEE (Alvi et al., 1999; Alvi et al., 2002; Alvi et al., 2003). Among them, mA116 scFv Ab was well characterized, showing sensitivity and specificity in recognition of VEE by immunoassay (Alvi et al., 2003). In order to further explore the potentiality of mA116 scFv Ab as an immunodiagnostic reagent for detecting VEE, the present inventors successfully fused a streptavidin-binding peptide (SBP) to mA116 scFv Ab by DNA recombinant technique. This confers a streptavidin-binding function on the mA116 scFv Ab and therefore obviates the need for conventional chemical biotinylation. Chemical biotinylation is commonly associated with impairment of the antigen-binding site of the Ab and it is hence desirable to use the recombinant SBP tagged mA116 scFv of the present invention as reagent to develop a simple, stable and efficient immunoassay for VEE.